Papers by Spencer Pelton
PLOS ONE
By 13,000 BP human populations were present across North America, but the exact date of arrival t... more By 13,000 BP human populations were present across North America, but the exact date of arrival to the continent, especially areas south of the continental ice sheets, remains unclear. Here we examine patterns in the stratigraphic integrity of early North American sites to gain insight into the timing of first colonization. We begin by modeling stratigraphic mixing of multicomponent archaeological sites to identify signatures of stratigraphic integrity in vertical artifact distributions. From those simulations, we develop a statistic we call the Apparent Stratigraphic Integrity Index (ASI), which we apply to pre- and post-13,000 BP archaeological sites north and south of the continental ice sheets. We find that multiple early Beringian sites dating between 13,000 and 14,200 BP show excellent stratigraphic integrity. Clear signs of discrete and minimally disturbed archaeological components do not appear south of the ice sheets until the Clovis period. These results provide support fo...
The Hell Gap National Historic Landmark, located on the northwestern plains of Wyoming, is one of... more The Hell Gap National Historic Landmark, located on the northwestern plains of Wyoming, is one of the most important Paleoindian archaeological sites in North America because it contains a stratified sequence of occupations spanning nearly the entirety of the Paleoindian period. Although Hell Gap is central to archaeological knowledge concerning North American Paleoindian chronology, consistently assigning component ages has been problematic due to conflicting radiocarbon determinations from individual strata, stratigraphic age reversals in age-depth relationships, and other issues related to the stratified open campsite. Toward resolving the Hell Gap chronology, we devised a procedure for correcting age-depth relationships for incorporation in chronostratigraphic models and then used the Bayesian age-depth modeling qprocedures in Bchron to estimate the ages of 11 stratified components present at Hell Gap Locality 1. We present these age estimates and discuss their significance to Paleoindian chronology. Notable aspects of our chronology include a revised age estimate for the Goshen complex, the identification of three Folsom components spanning the entirety of the Folsom temporal range, and relatively young age estimates for the Late Paleoindian Frederick/Lusk component(s) at Locality 1. More broadly, our study demonstrates a procedure for creating chronometric models of stratigraphically complicated open stratified sites of any type.
Prehistoric foragers living in the high elevations of the Colorado Front Range (CFR) transported ... more Prehistoric foragers living in the high elevations of the Colorado Front Range (CFR) transported ground stone tools at least 20 km from the CFR foothills to around 40 percent of sites in the subalpine forest and alpine tundra despite the sparse plant resources present in this region. This study is a distributional analysis that explains why there are so many ground stone tools in the CFR and how foragers developed strategies to efficiently utilize sparse high elevation plant resources. I draw expectations from the provisioning of place, which involves the efficient allocation of tools across space, and then test those expectations on a distributional data set of ground stone tools from the CFR. I conclude that foragers in the CFR practiced a generalist, bordering on intensive provisioning strategy in which a large number of sites were each provisioned with a small to moderate number of ground stone tools in
order to most efficiently utilize a broad suite of plant resources, as opposed to a single plant resource staple. Although the CFR does not contain alpine villages like other high elevation regions in the North American West, it contains evidence for a distinct form of residential settlement characterized by many short-term campsites provisioned with the tools necessary to support intensive plant resource exploitation.
The Wold Bison Jump (48JO966) is a communal bison (Bison bison) hunting site in Johnson County, W... more The Wold Bison Jump (48JO966) is a communal bison (Bison bison) hunting site in Johnson County, Wyoming. It likely represents
a single kill event precipitated by Great Plains foragers between A.D. 1433 and 1643. Operating the jump required
that prehistoric hunters drive stampeding bison up a steep slope in order to position them within a V-shaped drive line configured
to funnel them toward a cliff. Using iterative models of least cost paths, topographic cross-sections, and visibility
analysis, we test which landscape-embedded variables are optimized at the jump site as compared to other potential localities
across the study area. We find that this site’s placement is primarily explained by minimizing the distance at which the cliff
face is visible and secondarily by minimizing the cost of slope and curvature routes ascending into the drive lines. Our procedure
could hypothetically be used to predict optimal jump locations on similar landscapes.
Wold Bison Jump (48JO966) es un sitio de caza comunal de bisontes (Bison bison) localizado en el distrito de Johnson,
Wyoming. Este probablemente representa un único evento de caza por despeñamiento generado por cazadores-recolectores
de las Grandes Planicies, entre 1433 y 1643 d.C. Llevar a cabo el despeñamiento requirió que los cazadores prehistóricos
condujeran la estampida de los bisontes hacia una pendiente empinada, con el fin de posicionarlos dentro de una línea de
conducción en forma de V configurada para canalizarlos hacia un acantilado. Utilizando modelos interactivos sobre rutas de
menor costo, secciones topográficas transversales y análisis de visibilidad, testeamos cuáles de las variables incluidas en el
paisaje son optimizadas en sitio de despeñamiento, en comparación con otras localidades potenciales a lo largo del área de
estudio. Encontramos que la localización de este sitio se explica principalmente por la minimización de la distancia a la que
la pared del acantilado es visible y, en segundo lugar, por la reducción del costo de las rutas de pendiente y curvatura que
ascienden dentro de las líneas de conducción. Nuestro procedimiento podría ser utilizado hipotéticamente para predecir localizaciones
óptimas de despeñamiento sobre paisajes similares.
We argue that variation in Younger Dryas-aged fluting in the Great Plains and Rocky Mountains was... more We argue that variation in Younger Dryas-aged fluting in the Great Plains and Rocky Mountains was primarily conditioned by cold-mediated time budgeting concerns. Foragers that lived in cold environments had more time to flute projectile points during prolonged periods of downtime relative to those in warmer, southerly environments. We show that fluting meets the expectations of a time budgeting model because (a) its frequency is negatively correlated with temperature and (b) it was most often executed in interior spaces, presumably during prolonged periods of downtime. Aided by a channel flake use wear study, we conclude that fluting was not functional in a purely economic sense. Rather, it was a form of practice, enacted by those for whom wasting time was of little concern.
The Spring Canyon site (5LR205) is a multicomponent prehistoric campsite located in a foothills v... more The Spring Canyon site (5LR205) is a multicomponent prehistoric campsite located in a foothills valley within Fort Collins, Colorado. It is one of the largest, most diverse sites in the northern Colorado foothills, possessing over 1,700 artifacts spanning Folsom to Late Prehistoric times. This study is a synthesis of existing research at the site that combines several informal and formal investigations starting in the late 1930s. These investigations document the presence of a diverse array of chipped and ground stone tools, diagnostic projectile points, obsidian from the northern Plains and Southwest, ceramics, and buried artifacts and features. It is concluded that the Spring Canyon site served as an important residential base camp for much of prehistory, and that further excavation would likely reveal buried archaeological deposits. The case is made that the Spring Canyon site, though heavily impacted by historic practices, remains a valuable asset for its archaeological merit and its potential focus for public outreach. INTRODUCTION The Spring Canyon site (5LR205) is a multicomponent Native Ameri-can campsite located in Larimer County, Colorado, along the physiographic and ecological boundary separating the foothills of the Front Range and the shortgrass steppe of the Colorado Piedmont. It is situated adjacent to a prominent " water gap " in the hogback foothills, one of many such features along the foothills west of Fort Collins (Figure 1). In the northern Colorado foothills, water gaps are places where north/south-trending hogback ridges are breached
Palaeodemographic studies of animals using frequency distributions of radio-carbon dates are incr... more Palaeodemographic studies of animals using frequency distributions of radio-carbon dates are increasingly used in studies of Quaternary extinction but are complicated by taphonomic bias, or the loss of material through time. Current taphonomic models are based on the temporal frequency distributions of sediments , but bone is potentially lost at greater rates because not all sedimentary contexts preserve bone. We test the hypotheses that (i) the loss of bone over time is greater than that of sediment and (ii) this rate of loss varies geographically at large scales. We compiled radiocarbon dates on Pleistocene-aged bone from eastern Beringia (EB), the contiguous United States (CUSA) and South America (SA), from which we developed models of taphonomic loss. We find that bone is lost at greater rates than terrestrial sediment in general, but only for CUSA and SA. Bone in EB is lost at approximately the same rate as terrestrial sediments, which demonstrates the excellent preservation environments of arctic regions, presumably due to preservative effects of per-mafrost. These differences between bone and sediment preservation as well as between arctic and non-arctic regions should be taken into account by any research addressing past faunal population dynamics based on temporal frequency distributions.
The Granby Cache is a cache of 25 prehistoric flake tools found beneath the high water stand of L... more The Granby Cache is a cache of 25 prehistoric flake tools found beneath the high water stand of Lake Granby in Grand County, CO. The cache items are produced from Troublesome Formation chert, which was procured around 40 km from the cache. Most notably, many of the cache items are retouched into spokeshaves, suggesting this was a cached specialized toolkit.
Following Martin [Martin PS (1973) Science 179:969–974], we propose the hypothesis that the timin... more Following Martin [Martin PS (1973) Science 179:969–974], we propose the hypothesis that the timing of human arrival to the New World can be assessed by examining the ecological impacts of a small population of people on extinct Pleistocene megafauna. To that end, we compiled lists of direct radiocarbon dates on paleontological specimens of extinct genera from North and South America with the expectation that the initial decline of extinct megafauna should correspond in time with the initial evidence for human colonization and that those declines should occur first in eastern Beringia, next in the contiguous United States, and last in South America. Analyses of spacings and frequency distributions of radiocarbon dates for each region support the idea that the extinction event first commenced in Beringia, roughly 13,300–15,000 BP. For the United States and South America, extinctions commenced considerably later but were closely spaced in time. For the contiguous United States, extinction began at
ca. 12,900–13,200 BP, and at ca. 12,600–13,900 BP in South America. For areas south of Beringia, these estimates correspond well with the first significant evidence for human presence and are consistent with the predictions of the overkill hypothesis.
End scrapers are a widely recognized tool in the archaeological record, but their performance cha... more End scrapers are a widely recognized tool in the archaeological record, but their performance characteristics are poorly understood. We use experimental results and adapt marginal value theorem (MVT) for use in lithic studies to devise a formal model of end scraper performance that predicts the optimal time at which one should resharpen their end scraper under several scenarios of raw material abundance. Our model allows us to make explicit archaeological predictions related to end scraper use, time management, raw material economy, and end scraper accumulation rates.
This paper presents the results of investigations into the Olson site, a rock-walled communal hun... more This paper presents the results of investigations into the Olson site, a rock-walled communal hunting site located at Rollins Pass, Colorado, around 3600 m asl. It includes a projectile point chronology, chronometric dates, detailed maps of the site's walls and hunting blinds, metric attributes of the hunting blinds, an artifact tabulation, and a pollen/phytolith residue analysis of ground stone tools from the site. Prehistoric foragers used and remodeled the site for several thousand years beginning around 3,000 calibrated years BP.
This is my Master's thesis, which concerns the morphology, temporal affiliation, and spatial dist... more This is my Master's thesis, which concerns the morphology, temporal affiliation, and spatial distribution of ground stone tools from the high elevations (>2850 m asl) of the Colorado Front Range.
Grey Literature Reports by Spencer Pelton
This is a summary of surface recording, auger testing, and test excavations conducted at the Duck... more This is a summary of surface recording, auger testing, and test excavations conducted at the Duck Creek site (48AB2802) in August of 2013 and 2015 by students associated with the University Wyoming. In total these efforts documented 694 flakes, 60 prehistoric and protohistoric tools, 2 stone circles, and several historic artifacts. Most notably, the site contains a small, but diverse assemblage of Late Paleoindian projectile points, including Hell Gap, Pryor-stemmed, Foothills/Mountain, and Great Basin stemmed varieties, as well as a single metal projectile point. Test excavations documented the presence of well-stratified alluvial and colluvial sedimentary deposits extending from present to ca. 11,800 cal yr BP containing artifacts that span most of this time. Auger testing suggests that sediments spanning this time exist over an area of over 1,000 m2. The Duck Creek site holds great potential for clarifying a number of unresolved issues in northwest Plains archaeology, including Late Paleoindian Foothills/Mountain chronology, shifts in upland land use between the terminal Pleistocene and Holocene, and other issues related to use of this reoccupied upland base camp.
The Spring Canyon site (5LR205) is a multi-component prehistoric campsite located in a foothills ... more The Spring Canyon site (5LR205) is a multi-component prehistoric campsite located in a foothills valley within the city limits of Fort Collins, Colorado. The site has been surface collected by archaeologists since the late 1930s and likely many more times by amateur collectors. Over 1600 chipped and ground stone artifacts from three collections were analyzed, the results of which suggest that the site was used from Folsom to Early Ceramic times (10,900-1,000 rcybp). At times, its use was in the form of extended residential occupation that produced large amounts of locally-procured debitage and ground stone implements employed in the processing of plant and animals resources, along with a diversity of other stone tools, obsidian, and ceramics. The results of these analyses are presented, as well as those gleaned from recent augering of the site, which suggests the likely presence of stratified archaeological deposits. The case is made that the Spring Canyon site, though heavily impacted by historic practices, remains a valuable asset for its archaeological merit and potential as a site used for public outreach.
Conference Presentations by Spencer Pelton
The necessities for human survival include food, water, and shelter. Anthropologists have devoted... more The necessities for human survival include food, water, and shelter. Anthropologists have devoted a great deal of time to understanding how people procure the first two, but have devoted much less time towards understanding how they shelter themselves against the elements through the use of clothing and structures. Adaptations for extreme temperatures are necessary for survival in large portions of the world. Understanding how people deal with this may have huge explanatory potential for aspects of human behavior in the present and past. This study presents preliminary climate modeling of the exchange of heat between humans and the environment. I use data from the North American Regional Reanalysis (NARR), produced by the Earth System Research Laboratory (ESRL) at the National Oceanic and Atmospheric Administration (NOAA) (Messinger et al. 2005). All data are means for January and July between 1979 and 2014. January is assumed to be the coldest month of the year for most places in North America, and is thereby the time during which selective pressure for cold adaptations is greatest. Conversely, July is assumed to be the hottest month of the year for most places in North America, and is thereby the time during which selective pressure for warm adaptations is greatest.
Perhaps due to their near ubiquitous presence throughout time chipped stone scrapers are often v... more Perhaps due to their near ubiquitous presence throughout time chipped stone scrapers are often viewed as mundane and technologically simple components of prehistoric toolkits. Only through rigorous experimentation can we begin to understand contributions that endscrapers provide to somatic ends. However, their performance characteristics are little known. How long does an endscraper last? How many scrapers does it take to process a bison hide? Building on a previous experiment, this poster illuminates the performance characteristics of endscrapers. Expectations derived from marginal value theorem suggest the longer a resource is used the less effective it becomes, providing theory to test the optimal rate of endscraper resharpening? To this end we conducted an experiment in which dried bison hide was partitioned into analytic units and scraped. We collected data on dermis mass removed every 24 scrapes for thereby tracking the efficacy of the scraper bit throughout this task. Establishing this relationship provides a predictive measure for interpreting the role and intensity of scraper retouch.
Posters by Spencer Pelton
The Wold Bison Jump in Johnson County, Wyoming, is one of many prehistoric, mass kill sites scatt... more The Wold Bison Jump in Johnson County, Wyoming, is one of many prehistoric, mass kill sites scattered across the Plains. At Wold, a foraging basin of prime ungulate grazing habitat abuts the gently sloping backside of a bluff. Funnel-shaped drive lines of cairns extend across the top of the bluff towards a treacherous cliff. The drive was configured to constrain stampeding bison (Bison sp.) as prehistoric hunters communally drove them from the foraging basin to the precipice. Previous GIS analyses of bison jumps inductively analyze surrounding landscapes by classifying jump locations as known, unvarying focal points of analysis. While this approach can be informative, at Wold we attempt to obtain a more general understanding of how bison jumps operate. Using iterative models of least cost paths, topographic cross-sections, and visibility analysis, we test which landscape-embedded variables are optimized at Wold as compared to other potential localities across the study area. We find that this site’s placement is primarily explained by minimizing the distance at which the cliff face is visible and secondarily by minimizing the cost of slope and curvature routes ascending into the drive lines. Our procedure could hypothetically be used to predict optimal jump locations on similar landscapes.
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Papers by Spencer Pelton
order to most efficiently utilize a broad suite of plant resources, as opposed to a single plant resource staple. Although the CFR does not contain alpine villages like other high elevation regions in the North American West, it contains evidence for a distinct form of residential settlement characterized by many short-term campsites provisioned with the tools necessary to support intensive plant resource exploitation.
a single kill event precipitated by Great Plains foragers between A.D. 1433 and 1643. Operating the jump required
that prehistoric hunters drive stampeding bison up a steep slope in order to position them within a V-shaped drive line configured
to funnel them toward a cliff. Using iterative models of least cost paths, topographic cross-sections, and visibility
analysis, we test which landscape-embedded variables are optimized at the jump site as compared to other potential localities
across the study area. We find that this site’s placement is primarily explained by minimizing the distance at which the cliff
face is visible and secondarily by minimizing the cost of slope and curvature routes ascending into the drive lines. Our procedure
could hypothetically be used to predict optimal jump locations on similar landscapes.
Wold Bison Jump (48JO966) es un sitio de caza comunal de bisontes (Bison bison) localizado en el distrito de Johnson,
Wyoming. Este probablemente representa un único evento de caza por despeñamiento generado por cazadores-recolectores
de las Grandes Planicies, entre 1433 y 1643 d.C. Llevar a cabo el despeñamiento requirió que los cazadores prehistóricos
condujeran la estampida de los bisontes hacia una pendiente empinada, con el fin de posicionarlos dentro de una línea de
conducción en forma de V configurada para canalizarlos hacia un acantilado. Utilizando modelos interactivos sobre rutas de
menor costo, secciones topográficas transversales y análisis de visibilidad, testeamos cuáles de las variables incluidas en el
paisaje son optimizadas en sitio de despeñamiento, en comparación con otras localidades potenciales a lo largo del área de
estudio. Encontramos que la localización de este sitio se explica principalmente por la minimización de la distancia a la que
la pared del acantilado es visible y, en segundo lugar, por la reducción del costo de las rutas de pendiente y curvatura que
ascienden dentro de las líneas de conducción. Nuestro procedimiento podría ser utilizado hipotéticamente para predecir localizaciones
óptimas de despeñamiento sobre paisajes similares.
ca. 12,900–13,200 BP, and at ca. 12,600–13,900 BP in South America. For areas south of Beringia, these estimates correspond well with the first significant evidence for human presence and are consistent with the predictions of the overkill hypothesis.
Grey Literature Reports by Spencer Pelton
Conference Presentations by Spencer Pelton
Posters by Spencer Pelton
order to most efficiently utilize a broad suite of plant resources, as opposed to a single plant resource staple. Although the CFR does not contain alpine villages like other high elevation regions in the North American West, it contains evidence for a distinct form of residential settlement characterized by many short-term campsites provisioned with the tools necessary to support intensive plant resource exploitation.
a single kill event precipitated by Great Plains foragers between A.D. 1433 and 1643. Operating the jump required
that prehistoric hunters drive stampeding bison up a steep slope in order to position them within a V-shaped drive line configured
to funnel them toward a cliff. Using iterative models of least cost paths, topographic cross-sections, and visibility
analysis, we test which landscape-embedded variables are optimized at the jump site as compared to other potential localities
across the study area. We find that this site’s placement is primarily explained by minimizing the distance at which the cliff
face is visible and secondarily by minimizing the cost of slope and curvature routes ascending into the drive lines. Our procedure
could hypothetically be used to predict optimal jump locations on similar landscapes.
Wold Bison Jump (48JO966) es un sitio de caza comunal de bisontes (Bison bison) localizado en el distrito de Johnson,
Wyoming. Este probablemente representa un único evento de caza por despeñamiento generado por cazadores-recolectores
de las Grandes Planicies, entre 1433 y 1643 d.C. Llevar a cabo el despeñamiento requirió que los cazadores prehistóricos
condujeran la estampida de los bisontes hacia una pendiente empinada, con el fin de posicionarlos dentro de una línea de
conducción en forma de V configurada para canalizarlos hacia un acantilado. Utilizando modelos interactivos sobre rutas de
menor costo, secciones topográficas transversales y análisis de visibilidad, testeamos cuáles de las variables incluidas en el
paisaje son optimizadas en sitio de despeñamiento, en comparación con otras localidades potenciales a lo largo del área de
estudio. Encontramos que la localización de este sitio se explica principalmente por la minimización de la distancia a la que
la pared del acantilado es visible y, en segundo lugar, por la reducción del costo de las rutas de pendiente y curvatura que
ascienden dentro de las líneas de conducción. Nuestro procedimiento podría ser utilizado hipotéticamente para predecir localizaciones
óptimas de despeñamiento sobre paisajes similares.
ca. 12,900–13,200 BP, and at ca. 12,600–13,900 BP in South America. For areas south of Beringia, these estimates correspond well with the first significant evidence for human presence and are consistent with the predictions of the overkill hypothesis.